When constructing/modifying a feed or stand-off pad, it is important to consider all options and to design the effluent disposal system at the same time.

Feed pads

Pad design

The size and shape of the pad depends on the number of cows, hours it is likely to be used for, and the area of land available – close to the yard with good cow flow is ideal.

The cows' ability to lie down is the main factor when it comes to determining the area needed, if the pad is to be used for stand-off. Cows need to be able to lie down for at least eight hours per day.

Effluent

The design and infrastructure needs to include effective collection and treatment/disposal of effluent from the pad, entry/exit/transit races and silage/supplementary feed storage bunkers. Regional rules for effluent disposal from these areas are the same as those for effluent from the dairy.

Characteristics

The main differences between effluent from a feed/stand-off pad and the dairy are:

Higher solids content;

Higher volume; and

Higher nutrient content.

Volume

The volume of effluent generated from a pad:

Varies depending on the construction material of the pad;

Is directly related to stock numbers and the length of time animals are on the pad;

Is increased by lost feed solids when supplements are fed;

Is directly related to the method used for cleaning, that is, scraping versus washing;

Can be much higher than from the dairy alone; and

Is greatly increased during rain (if the pad has no roof).

Stormwater

Effluent systems must be designed to handle stormwater volumes when it's not practical to divert. In Northland, rainfall events with intensities of 10mm/hour occur frequently and falls of 3-60mm/hour are common.

For example: 10mm falling on a 1000m2 pad will generate 10m3 of stormwater. This is the same as the total daily effluent volume from a dairy milking 200 cows.

Stormwater from the pad can only be diverted:

When stock are not on the pad;

When the pad is clean.

Some Northland farmers have fitted roofs to existing pads to improve cow comfort and reduce effluent volumes – by decreasing stormwater on the pad and dry-scraping the effluent.

Covered pads

Covering pads and dry-scraping the effluent, greatly decreases both effluent and water volumes.